Hi Jake,
On Tue, Jul 8, 2025 at 12:12 AM Jacob Lifshay <programmerjake-at-gmail....@ffmpeg.org> wrote: > > I'm currently writing a .mcc muxer, it currently translates from eia-608/708 > to full vanc packets before outputting a .mcc file: > https://github.com/programmerjake/FFmpeg/tree/add-mcc-mux I took a quick look at your branch. So this is a good start, IMHO... Note that I took a look at the MCC demuxer last year, and it's got a bunch of issues where the parsing makes a bunch of assumptions (e.g. doesn't filter out other VANC types which might be present in an MCC such as AFD). And it only extracts 608 (i.e. doesn't handle 708). I'm mentioning this should you try using the MCC demuxer while developing a muxer. The demuxer would need some love before I would trust it for anything in production. > I want to add the ability to the mxf and mcc muxers/demuxers to keep the full > vanc data when doing stream copies, what do you think is the best way to do > that? > > * add a new AVCodecID for mxf vbi_vanc_smpte_436M > * change the muxers/demuxers to be able to use AV_CODEC_ID_SMPTE_KLV or > AV_CODEC_ID_SMPTE_2038 (they hold the full vanc packets, right?) I would stay away from KLV entirely. The SMPTE 2038 standard does support all VANC data types, but support in ffmpeg really is only oriented around passthrough (i.e. routing 2038 packets from an input TS to an output TS). It currently doesn't attempt to decode the 2038 payloads into something easier to work with. I've built stuff like bitstream filters that take in 2038 packets and use libklvanc to parse out the individual VANC sections, but none of that is upstream (happy to send you links to where it can be found in my public GitHub repo). In other words, you might have difficulty working with the structures if you have to deserialize them and reserialize them when passing them between modules (although libklvanc does technically support both). > * use the mxf vbi_vanc_smpte_436M stream as is -- AV_CODEC_ID_NONE and with > vbi_vanc_smpte_436M in the metadata I can't speak to whether this would be a good idea. > additionally, it'd be nice to be able to output a eia-608/708 stream to mxf, > so that would either need a codec/filter of some sort to translate to full > vanc data in whatever format the mxf muxer ends up supporting, or to have > that translation built-in to the mxf muxer, like it is built-in to the mxf > demuxer (with eia608_extract). I've done this sort of thing with bitstream filters. The BSF takes in 2038, extracts the 608, and outputs 608 packets. You could do something comparable for MXF. Also, I set up the muxers to automatically insert the BSF if needed, which makes it painless for the user. The 608/708 stuff is kind of a mess in terms of what is in those payloads. Some modules will expect 608 only, others will contain tuples that include 708. And there continues to be no easy way to go back and forth between 608 packets and SEI data embedded within the video stream (in either direction: SEI to 608 packet streams, or 608 packet streams into SEI). Devin -- Devin Heitmueller, Senior Software Engineer LTN Global Communications o: +1 (301) 363-1001 w: https://ltnglobal.com e: devin.heitmuel...@ltnglobal.com _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
